The public or quasi-public real time distribution of messages has become an increasingly popular mode of communication. Thus, microblogging applications like Twitter™ support the public broadcast of short textual messages; social networking applications support the posting of status messages that are made available to large social networks; and geo-locative applications like FourSquare™ allow its users to “check in” to places, and broadcast their locations. Regardless of the application, the basic idea is that a message is made available to a very large set of people who can use various methods to tune into the subset of messages that interest them.
Messages broadcast in this way have a variety of uses. For instance, it has been observed that in public emergencies many people broadcast requests for help or reports of a problem at a particular time and place. For instance, a person in need of help may report that the street in front of her house is flooded and water is coming in the basement. For the purposes of this discussion it is useful to think about recipients of a broadcast message falling into three classes:                There may be potential respondents who can respond to the message in a way that is useful to the sender, those who may see the person's message and come over to help; or, personnel from the local volunteer fire department may respond in the same way.        There may be potential beneficiaries who can profit from the information, but who cannot provide a response that is useful to the sender. Personnel who work for public transit may re-route a bus away from the street that has been reported as flooding.        There may be potential routers who see the message and who have the knowledge and ability to bring it to the attention of additional potential respondents and/or potential beneficiaries.        
A broadcast message has visibility to a wide array of people, who may respond to it in different ways, for instance, by assisting the sender, deriving some other value, or forwarding the message. Consider more closely the potential beneficiaries—those whose receipt of the message will not benefit the sender. There may be two cases in the above example. The first case is when the value that the potential beneficiary gains from the message does not harm the sender. For example, a publicly broadcast message about a particular problem may, in combination with many such requests from different points in a city, provide a valuable picture of the situation.
Knowing the distribution of reports of flooding or power outages may help emergency responders identify districts that have been hit particularly hard, and that may need extra support, equipment, or attention to its infrastructure. Similarly, such messages may help individuals in the same areas prepare for or diagnose similar situations.
Although this does not help the sender of the message, it does contribute to the public good. On the other hand, some potential beneficiaries may derive value from a message that results in harm to its sender. A public message saying that the electricity is out at 111 Eleventh Street may bring help from the utility company, but it may also attract looters. A report of an accident at 5th and Main may bring an ambulance, but it may also attract onlookers who cause a traffic jam and impede the ambulance. And so on.
In this sense, certain categories of information—location information, time information, personal identity information—are likely to be sensitive. There are several approaches to countering the effects of disclosing sensitive information. One is simply to not broadcast it. However, this approach quashes any public good that can be obtained by public beneficiaries, and also lowers the likelihood that it will be seen and acted upon by potential routers, making the sender less likely to benefit from it. A second approach is to hide the sensitive information from public view by, for example, encrypting it. In such a scenario, intended recipients might be supplied in advance with means of decrypting such messages. This approach has at least two drawbacks. First, it requires advance preparation (e.g., learning about and obtaining encryption keys), which is logistically complicated for the sorts of broad public uses illustrated above in the crisis response scenario. Second, hiding the sensitive information means that many potential beneficiaries would not benefit and potential routers would not know who the messages ought to be routed to.
Therefore, the present disclosure recognizes that a need exists for a way of protecting sensitive information in publicly transmitted messages without completely hiding it. The present disclosure demonstrates a method of progressive obfuscation and de-obfuscation of public messages.